shunt trip

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iwire

iwire

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Ingenieur said:
what if the smoke doesn't go off and the sprinkler does
unlikely but has happened due heat build up at the top of the shaft
does the sprinkler stop or recall the elevator?
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What if? I love a good game of what if. :)

What if the smoke does not go off on a landing with smoke or fire and the elevator tries to drop passengers off there? :)


I thought, and I could be wrong, that in typical designs it is assumed smoke detectors will function.
 
I

Ingenieur

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Location
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iwire said:
What if? I love a good game of what if. :)

What if the smoke does not go off on a landing with smoke or fire and the elevator tries to drop passengers off there? :)


I thought, and I could be wrong, that in typical designs it is assumed smoke detectors will function.
Click to expand...


The heat detector shunt trip in a sprinklered shaft is code
it's funny a juristiction would omit this requirement

Article and photos by Gregory Havel
In multistory buildings protected by automatic fire sprinkler systems, building codes require sprinkler heads to be located at the top of the elevator hoistway to protect the vertical shaft and the elevator car inside it and in each elevator machine room.

Most states and other jurisdictions have adopted American Society of Mechanical Engineers (ASME) A17.1 and A18.1 standards for the installation and operation of elevators, either as published by ASME or with additions or exceptions.

If a sprinkler head were to discharge water into the elevator hoistway or machine room during operation, it is likely that the elevator would operate unpredictably because of water on the control devices. Before power shunt trips were required for sprinklered elevator hoistways and machine rooms, elevators that became wet from sprinkler discharge were known to run with doors open, to miss floor landings, to stop between floors, and to crash into the elevator pit or into the top of the hoistway.

A power shunt trip in an elevator operates simply and reliably. Heat detectors are located in the machine room and at the top of the hoistway, within 24 inches of each sprinkler head. These heat detectors are set at a lower temperature and are more sensitive to temperature change than the sprinkler heads, and will signal that sprinkler discharge is imminent. The elevator’s main power shunt trip breaker will trip and stop the elevator car wherever it is, even between floors, so that it will not malfunction when the sprinkler discharges. This power shunt trip can only be reset manually at the elevator controller. (Some jurisdictions may permit a delay in operation of the power shunt trip so that the elevator car can move to its primary recall floor level and open its doors. See National Fire Protection Association (NFPA) Standard 72 (2010), National Fire Alarm and Signaling Code, Article 21.4 and Appendix A.21.4.1; and NFPA Standard 70 (2008), National Electrical Code, Article 620.51-B, for details.)
The ASME and NFPA standards and codes consider the occupants of an elevator car that is stopped between floors or that is evacuated at the nearest floor level to be at less risk than they would be if the elevator continued to operate during fire sprinkler discharge.
 
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Ingenieur

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Earth
2.8.2.3 Sprinkler systems conforming to NFPA 13or the NBCC, whichever is applicable (see Part 9), shallbe permitted to be installed in the hoistway, machineroom, and machinery spaces, subject to the requirementsof 2.8.2.3.1 through 2.8.2.3.4.


2.8.2.3.1 All risers and returns shall be locatedoutside these spaces. Branch lines in the hoistway shallsupply sprinklers at not more than one floor level. Whenthe machine room is located above the roof of the build-ing, risers, return pipes, and branch lines for the machineroom sprinkler(s) shall be permitted to be located in thehoistway between the top floor and the machine room.


2.8.2.3.2 In jurisdictions not enforcing the NBCC,means shall be provided to automatically disconnect themain line power supply to the affected elevator uponor prior to the application of water from sprinklerslocated in the machine room or in the hoistway morethan 600 mm (24 in.) above the pit floor. This meansshall be independent of the elevator control and shallnot be self-resetting. The activation of sprinklers outsideof the hoistway or machine room shall not disconnectthe main line power supply.


2.8.2.3.3 Smoke detectors shall not be used toactivate sprinklers in these spaces or to disconnect themain line power supply.
 
gadfly56

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Ingenieur said:
It's the passengers who will be disappointed...for a short while
their heirs lawyers will not be

it's code
not optional
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You just don't get that jurisdictions are free to adopt, amend, or write any code they please. Or adopt no codes. How is this hard to understand?
 
Sahib

Sahib

Senior Member
Location
India
iwire said:
What if the smoke does not go off on a landing with smoke or fire and the elevator tries to drop passengers off there? :)
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Then the passengers would regret how fated they are and their lawyers would sue the management for lack of proper maintenance.:)
 
luckylerado

luckylerado

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Location
Lake of the Ozarks
The Department of Buildings' Elevator Division has the references posted right on their webpage. I have done some searching and I see no evidence that NYC has adopted any changes to the elevator code as it is listed there. Can someone post some code language to back it up.

I know life long electricians that would not know how or why to shunt trip an elevator even though it has happened under their nose a dozen times.
 
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D

donaldelectrician

Senior Member
donaldelectrician said:
Had 3 Shunt Trips for elevators , fed 347 V TRANS , at each elevator VFD Loco , New Sky Boxes ,

Homestead Motor Speedway … 2005 … Don
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So is this a thing of the Past . I had 3 Shunt Trips at Elevator Closets VFD 347V Trans . Feeds , 2005 Homestead Motor
Speedway Sports Complex , 30 New Skyboxes , Track Lighting . Pit Lighting . Media Center . Helle Port .


Or still common ?


Don
 
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ron

ron

Senior Member
Location
New York, 40.7514,-73.9925
luckylerado said:
The Department of Buildings' Elevator Division has the references posted right on their webpage. I have done some searching and I see no evidence that NYC has adopted any changes to the elevator code as it is listed there. Can someone post some code language to back it up.

I know life long electricians that would not know how or why to shunt trip an elevator even though it has happened under their nose a dozen times.
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I'm guessing that there are relatively little combustibles in the shaft, but NYC doesn't allow sprinklers in the shaft either.
You will find in the NYC building code section 903.2 "Sprinklers shall not be permitted in elevator machine rooms and elevator machinery spaces." This is interpreted as being that the shaft is part of elevator machinery spaces
 
gadfly56

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
luckylerado said:
The Department of Buildings' Elevator Division has the references posted right on their webpage. I have done some searching and I see no evidence that NYC has adopted any changes to the elevator code as it is listed there. Can someone post some code language to back it up.

I know life long electricians that would not know how or why to shunt trip an elevator even though it has happened under their nose a dozen times.
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OK, I did a little digging, and it appears that confusion abounds. NYC still has elevator shunt trips on the books. Here is a rule making, not dated, amending the 2010 edition of NFPA 72 that permits a time delay if there is a shunt trip installed. Here is a later amendment to the building code that requires a time delay. And yet the building code prohibits sprinklers in hoistways (3008.3.2). In each case just do a search in the document for the word "shunt" or "sprinkler". The last reference is at the NYC building department web site, so I suppose it's definitive.

Also keep in mind that in the rest of the world, if the elevator hoistway has 2-hour fire rated construction, the building code(s) allows the deletion of sprinklers in the hoistway.
 
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Ingenieur

Senior Member
Location
Earth
iwire said:
Code is not what you say is code.

Code is what the local area has adopted.
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Mass has adopted it
if shaft is sprinklered shall be shunt trip (actually main line power removed)
it was actually a seminar topic this morning

whether the shaft oos sprinklered or not is building code
 
Sahib

Sahib

Senior Member
Location
India
Who demands to place a sprinkler head in lift machine room or lift hoist way, the insurance agency?
 
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iwire

iwire

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Location
Massachusetts
Ingenieur said:
Mass has adopted it
if shaft is sprinklered shall be shunt trip (actually main line power removed)
it was actually a seminar topic this morning

whether the shaft oos sprinklered or not is building code
Click to expand...

That's great, but it was RI that I said has disconnected the shunts. :p
 
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